Vehicle suspension and steering system variations for 4 or 3-wheel vehicle designs have been extensively researched and refined. Although many improvements have been made to date, most modem systems continue to be plagued, to some extent, by problems of bump/brake steer, alignment difficulties, inaccurate turning radius angles, alignment changes during road irregularities, anti-roll limitations, lack of adjustability, excessive driver steering strength requirements (often leading to need for power steering), weight, lack of adjustability of suspension rate, lack of adjustability of anti-roll, high unsprung weight and assembly bulkiness. Some of these drawbacks of conventional systems are described below.
Most conventional vehicle steering systems (especially automotive) use a design that includes a tie rod attaching to a pivoting arm to the wheel knuckle and spindle. In a conventional steering system, while the vehicle is driving directly forward, the tie rod is angled 90 degrees from the steering arm pivot and maximal force is transferred from tie rod to steering arm due to this angle. As the vehicle turns (either right or left), the angle between the tie rod and steering arm pivot changes and the efficiency of transfer of force from tie rod to steering arm is diminished due to the change in angles. The end result of this loss in efficiency of transferred forces to the steering arm is an increase in the steering force needed from the driver's steering input (or increased load on the power steering unit).
The (unequal length) double wishbone (or unequal length A-arm) suspension system is considered by many, especially in the racing field, as the gold standard by which other suspension systems are measured. This type of suspension has favorable aspects including overall strength and its ability to control camber during vertical suspension movements. Drawbacks of this type suspension include bump steer (Ackerman angle and steering direction changes during bumps), brake steer (steering angle changes during braking or undesirable steering turning forces transferred to the driver or power steering unit during braking), caster changes during road bumps (causing wandering of the tire/wheel and steering angle changes), toe-in changes during road bumps (causing inaccurate Ackerman angles, steering wander, loss of traction and tire wear).
High unsprung weight is another drawback of most conventional suspension systems. Conventional suspensions often incorporate a spring and shock absorber that rest on an A-arm of the suspension, thus contributing to the unsprung weight of the vehicle. Some (usually rear-engine) racing vehicles minimize unsprung weight by using a pushrod or pullrod to transfer forces from vertical suspension movement to a spring and shock absorber mounted on the sprung portion of the vehicle.
Changing of the springs, and therefore changing of the spring rate, of conventional suspension systems usually requires lifting of the vehicle and wheel removal. This is a cumbersome process which makes fine-tuning or frequent changes of spring rate very inconvenient and time-consuming.
Conventional anti-roll systems often incorporate a torsion (anti-roll) bar that resists the tendency of the vehicle to lean during turns. These anti-roll bars are typically non-adjustable metal bars that pivot on a frame bushing and attach to the A-arms of the suspension. These anti-roll bars contribute to unsprung (and total) suspension weight.
Cylindrical-suspension-component-in-housing (sliding) type suspensions have been designed for aircraft, bicycles, snowmobiles and, to a lesser extent, automobiles and other vehicles. The designs for automotive vehicles have been limited in number and have not been successful thus far. Cylindrical-suspension-component-in-housing designs may have not adequately overcome enough of the limitations of conventional suspension systems (as discussed above) to justify retooling. Other reasons for the lack of success with cylindrical suspension component-in-housing designs may be the new problems encountered with some designs including bulkiness, lack of strength, lack of adequate steerability, inadequate lubrication mechanisms, difficulty integrating anti-roll mechanisms and poor durability.
As discussed above, conventional steering/suspension/anti-roll systems have many limitations which have been a challenge to overcome, even after some attempts at cylindrical-suspension-component-in-housing designs.